WO2017178290A1

WO2017178290A1 - Method for treating domestic supply water installations

Info

Publication number: WO2017178290A1
Application number: PCT/EP2017/058042
Authority: WO
Inventors: Pierre Descloux
Original assignee: Dipan Sa
Priority date: 2016-04-15
Filing date: 2017-04-04
Publication date: 2017-10-19
Also published as: CN109071285A; EP3231774A1; US20190128541A1; CN109071285B; US10816221B2; EP3231774B1

Abstract

A method for treating a domestic supply water circuit, that comprises injecting a treatment product comprising silicates into the water flowing in said circuit in order to form a film on the inner surfaces of said circuit, characterised in that the injection of the treatment product comprises at least one step of injecting silicates at a concentration of between 100 and 200,000 milligrams per litre (mg/L) into the water flowing in said circuit for a period of between 10 minutes (min) and 24 hours (h), the flow rate of water flowing in the circuit being controlled within a range of between 0.05 and 100 litres per minute (L/min) and the temperature of water flowing in the circuit being controlled within a range of between 40 and 65 °C.

Description

PROCESS FOR TREATING SANITARY WATER FACILITIES

The present invention relates to a method of treating the inner surface of sanitary water mains.

A method for the preventive treatment of corrosion, oxidation and deposition in sanitary water circuits by the injection of silicates is known from EP 1 '432'534B1. Solutions of sodium silicates are injected into the sanitary water networks to limit the phenomenon of corrosion inside the pipes. The injection takes place during the operation of the sanitary water network, continuously and in proportion to the flow of water, nevertheless, in concentrations ensuring compliance with food standards. The presence of silicates in the water curbs corrosion by the formation of a thin protective film which is deposited on the inner surfaces of the pipes. The presence of this protective film limits the chemical exchanges between the water and the pipe. This process is effective for treating all materials undergoing corrosion phenomena, including ferrous alloys or copper alloys.

In general, a diagnosis is first made in order to provide a description of the state of the water network to be treated. This diagnosis makes it possible to define the level of degradation of the pipes. Depending on the condition of the pipes, cleaning them can be useful, especially to eliminate oxidation and scale deposits that can obstruct the pipe, degrade the quality of the water, accelerate the degradation of pipes by their presence (especially in the case of crevice corrosion) and may interfere with the good formation of the film during the treatment step.

A known method for cleaning pipes is an injection of acids allowing the dissolution of the deposits inside the pipes. This approach has the advantage of being simple to use and effective. However, in the case of relatively advanced corrosion, there may be the presence of local micro-perforations pipes related to the phenomenon of pitting corrosion in the case of copper, or crevice corrosion in the case of ferrous alloys. These micro-perforations are often blocked by deposits of oxidation and scale themselves, thus generating no leakage. In these situations, acid cleaning dissolves these little "plugs" and micro-leaks appear.

One approach to address this problem would be to identify the affected sections of pipe and to replace or sleeve the failed elements. Nevertheless, this represents an extremely long and complex operation as much to identify the position of the leak (because the pipes are often walled and the leakage rate is low) than to repair it.

Another problem related to chemical cleaning is the coloring phenomenon (red water, turbidity) of the water during the restarting of the network. Despite the neutralization of the cleaning products and the rinsing carried out after the cleaning, sometimes there is the presence of a colored water, resulting from a very rapid reactivation of the oxidation of the interior of the pipe exposed by the cleaning .

Once the pipe is cleaned, it can proceed to its preventive treatment with corrosion by continuous injection of silicates. The concentration of silicates must respect the legal food standards in force in different countries. For silicates in drinking water in Switzerland, the Swiss Food Manual (MSDA) and the Federal Ordinance on Foreign Substances (OSEC) provide a tolerance value for added silicates (for protection against corrosion) which is 5 milligrams of silicon per liter of water (mg of Si / L of water) in standard treatment and 10 mg of Si / L of water in the short term (not exceeding 3 months). Although food standards are not the same in all countries, practice in Switzerland is considered a safe practice for human health and can serve as a reference. At these concentrations, the rate of formation of the silicate film may be too slow to form a protective layer sufficient to overcome the aforementioned problems. Moreover, the formation rate of the above-mentioned layer is difficult to control and depends on various parameters, in particular:

• the amount of water consumed;

• flow rate and flow velocity;

• the temperature - the performance of the deposition being lower in cold water than in hot water;

And what we will call environmental parameters such as the composition of the water, including its pH and hardness, the materials that make up the pipe, and other phenomena such as the presence of stray currents. Thus, all of the elements having an influence on the above-mentioned layer formation, but nonetheless non-controllable by the present invention, are grouped together in environmental parameters.

A rough surface condition of a degraded pipe may also disturb the deposition of a suitable protective film, for example because of local disturbances to the water flow.

Continuous treatment as proposed in EP1,432,534B1 may not be sufficient to eliminate or reduce sufficiently certain micropollutants or pathogens. able to migrate sanitary water pipes to consumable water. The possible sources of these micropollutants and of pathogenic germs are the various elements composing the conduits, namely:

- The pipes themselves.

- Welds and joints related to pipe assembly.

- The various equipment necessary for the proper functioning of a hydraulic network such as valves, valves or flowmeters.

Among the undesirable micropollutants, mention may be made, in a non-exhaustive manner:

- Lead, which can come from different elements, such as lead pipes, tin-lead solders, brass accessories and PVC pipes.

- Cadmium, chromium and nickel that can come from low-alloy copper elements.

- Zinc that can come from galvanized steel elements.

- Vinyl chlorides that can come from PVC pipes.

- Benzopirenes that can come from polyethylene pipes.

Some pathogens like to grow on the inner surface of pipes and in multiple nooks, such as Legionella.

A general object of the invention is to provide a method of treating the inner surface of sanitary water supply pipes to ensure good water quality and / or to offer good protection against degradation of water. pipes.

It is advantageous to provide a process that provides good protection against corrosion and deposit formation.

It is advantageous to provide a method for limiting the contamination of the sanitary water by pollutants and pathogens present in the water circuits.

It is advantageous to provide a method for repairing micro-leaks.

It is advantageous to provide a method for rapidly preventing the formation of corrosion after cleaning a sanitary water installation.

It is advantageous to provide a process increasing the reliability and efficiency of a continuous treatment by injection of silicates according to food standards, for the prevention of corrosion and / or the formation of deposits in sanitary water circuits. . In the present invention, there is described a method of treating a sanitary water circuit, comprising injecting a treatment product comprising silicates into water circulating in said circuit to form a film on the surfaces. interiors. The injection of the treatment product comprises at least one silicate injection step at a concentration of between 100 and 200,000 milligrams of silicon per liter of water (mg of Si / L of water) in the water circulating in said circuit. for a period of less than 48 hours (h), the flow rate of water flowing in the circuit being adjusted in a range between 0.05 and 100 liters per minute (L / min) and the temperature of water circulating in the circuit being adjusted in a range between 35 and 65 ° C.

Advantageously, the rapid impregnation of silicates on the inner surface of the pipe makes it possible to provide a resistant and reliable layer over the entire inner surface, and to seal any micro-perforations. This impregnation layer also serves as an excellent base for continuous treatment that feeds this base layer to maintain long-term protection. Also, the rapid formation of an optimal layer makes it possible to:

- limit the migration of micropollutants from pipes, welds and pipe fittings to consumable water, and

- prevent / limit the contamination of the consumable water by pathogenic germs developing in the pipes.

The method according to the invention allowing the almost immediate formation of a protective film which thus avoids contact between the water and the pipe, is very effective in limiting the migration of micropollutants to the consumable water. Furthermore, the rapid formation of a film on the inner surface of the pipes, blocking the small cavities and reducing the roughness of the surface, makes it possible to limit the development of these seeds by:

o filling cavities (germ development zones are condemned) o imprisonment of germs (existing germs can be covered by the film).

According to one embodiment, the concentration of silicates in the water circulating in said circuit is adjusted to between 500 and 50 mg / l, preferably between 1 and 100 mg / l of water.

According to one embodiment, the duration of an injection step is between 30 minutes and 12 hours, preferably between 1 hour and 4 hours, for example around 2 hours.

According to one embodiment, the flow of water flowing in the circuit is adjusted in a range between 0.05 and 10 L / min. According to one embodiment, the temperature of the water circulating in the circuit is adjusted in a range between 40 and 60 ° C, preferably between 50 and 60 ° C, for example around 55 ° C. Advantageously, adjusting the temperature in these ranges makes it possible to form the silicate layer more rapidly and to make it more homogeneous.

According to an advantageous embodiment, the method comprises at least two treatment product injection cycles, preferably at least three cycles of treatment product injection. Advantageously, the plurality of cycles makes it possible to improve the resistance of the layer of silicates by improving the crystallization by successive thin layers.

According to an advantageous embodiment, the method comprises at least one drying step by emptying the circuit water for a period between 5 minutes and two hours, after at least one of the treatment product injection cycles. Drying advantageously makes it possible to increase the resistance of the silicate layer formed on the inner surface of the pipes.

According to one embodiment, a drying step is carried out after each treatment product injection step.

According to one embodiment, the duration of a drying step is between 10 minutes and 1 hour, preferably between 20 minutes and 40 minutes, for example around 30 minutes.

According to one embodiment, the sanitary water circuit comprises a cold water circuit, and the method comprises a step of interconnecting the cold water circuit with a hot water source configured to circulate the water. hot in the cold water circuit during injection of the treatment product. This advantageously makes it possible to optimize the impregnation process for the cold water circuits.

According to one embodiment, the sanitary water circuit comprises a cold water circuit and a hot water circuit, and the method comprises a step of interconnecting the cold water circuit with the configured hot water circuit. to circulate the hot water in the cold water circuit during the injection of the treatment product. This advantageously makes it possible to optimize the impregnation process for the cold water circuits in an economical way, since the hot and cold water circuits are treated simultaneously. In one embodiment, the hot water source may be an off-grid external source.

According to one embodiment, the silicates are in the form of sodium silicates in solution, in particular comprising mainly (Na ₂ O) _n + SiO ₂ , n being between 1.6 and 3.8.

According to one embodiment, the method may comprise a step of cleaning the sanitary water circuit before the injection of the treatment product comprising silicates, the cleaning step comprising an injection of acid into the water circuit. health.

According to one embodiment, after the specific treatment steps mentioned above, it is possible to carry out a continuous injection of the treatment product comprising silicates in an amount proportional to the volume of water entering the sanitary water circulation circuit, the maximum amount of product injected does not exceed a value set by the food standards.

Other objects and advantageous aspects of the invention will appear on reading the detailed description of embodiments and drawings.

Fig. 1 is a diagram generally illustrating a method for diagnosing and treating sanitary water installations according to one embodiment of the invention;

Fig. 2 is a diagram illustrating a method of treating a domestic water installation according to one embodiment of the invention;

Fig. 3 is a graph illustrating time processing steps of a portion of the method according to one embodiment of the invention;

Fig. 4 is a schematic view of a sanitary water installation configured for a treatment method according to a first embodiment of the invention;

Fig. 5 is a schematic view of a sanitary water installation configured for a treatment method according to a second embodiment of the invention;

Fig. 6 is a schematic view of a sanitary water installation configured for a treatment method according to a third embodiment of the invention; Fig. 7 is a schematic view of a sanitary water installation configured for a treatment method according to a fourth embodiment of the invention.

Referring to the figures, a method of treating a sanitary water circuit comprises injecting a treatment product comprising silicates into water flowing in said circuit to form a film on the interior surfaces of said circuit. This treatment process may be preceded by a diagnostic step S0 of the state of the water mains, and depending on the results, a decision on the processes to be carried out as illustrated in figure 1.

Referring to FIG. 2, a first step S1 comprises the preparation of the treatment plant and the configuration of the sanitary water network for the impregnation process S3, S4. The configuration of the network may include in particular the interconnection of a cold water circuit with an external water heater and / or the interconnection of a cold water circuit with a hot water circuit of the water network. sanitary of a building or part of a building, so that the temperature of the cold water circuit can be increased to an optimum temperature for the impregnation process. The temperature can be adjusted by mixing control (flow) of hot water and cold water injected into the circuit under treatment during the impregnation process. Various automatic adjustment means of hot and cold water flow input to stabilize the output temperature, well known per se, can be used in the treatment plant to adjust the treatment temperature.

The treatment method according to the invention comprises a process for impregnating S3, S4 with a silicate film which is carried out outside the normal operation of the water network. The impregnation process S3, S4 is punctual and is preferably carried out in less than 12 hours to limit the out of operation of the sanitary water network. The treatment process may also comprise, after the impregnation process S2, a continuous injection process S6 of the treatment product comprising silicates in an amount proportional to the volume of water entering the domestic water circuit, the maximum quantity of injected product not exceeding a value set by the food standards. Prior to impregnation, the treatment method may further comprise a cleaning method S2 of the domestic water circuit. The cleaning step can in particular include the injection of acid into the sanitary water circuit.

The positioning of the impregnation process S3, S4 is presented in FIGS. 1 and 2. It is carried out: • In general, after a cleaning process S2, but also at any other time during the life of a sanitary water system, for example, in the case of a preventive treatment on a part of a new circuit.

• In general, prior to a S6 continuous treatment operation that complies with food standards, but also sometimes prior to untreated operation, such as, for example, in the case of a healthy operation undergoing tartar cleaning, and where an impregnation is applied to avoid problems of colored water.

Unlike the subsequent stages of overdose and continuous treatment S6, the sanitary water network is not in operation during the impregnation process S3, S4. This makes it possible to apply various procedures for injecting silicates as well as using different values of physical and chemical parameters for injecting silicates, which greatly facilitates the formation of the protective film.

This process is also ideally composed of an alternation of two stages:

• A S3 injection step of a silicate solution in the pipes in concentration exceeding the food standards and at temperatures ranging between 35 and 65 ° C, preferably between 40 and 60 ° C. This injection period aims to quickly deposit a layer of silicates.

• A drying step S4 of the protective film which aims to harden and stabilize the layer by desiccation. This step favors the holding of the protective film, it is however not essential, the impregnation process can also be performed only by an injection step.

Ideally, the impregnation procedure comprises a plurality n of cycles, in particular at least two cycles, but preferably three cycles, or more. Each cycle comprises an injection step S3 which can be followed by a drying step S4, or simply a waiting period without emptying the water circuits. The drying step can be performed by emptying the water circuit and allowing air to enter the circuit, followed by a waiting time which can be between 5 minutes and 4 hours, but which has a duration preferably between 10 minutes and 1 hour, for example between 20 and 40 minutes. In the example illustrated in Figure 3, there are three injection cycles of about two hours each, and three drying cycles of about 30 minutes each.

Alternatively, one or more of the drying steps may comprise forced blowing of air, or a gas promoting drying of the layer of the treatment product, in the circuit under treatment. The forced blowing can be carried out for example by means of an air compressor or by means of a bottle of compressed gas.

The adjustable parameters of the S3 injection process are as follows: the number of cycles, the duration of the injection phase, the concentration of silicates (calculated in mg of Si / L of water), the water flow rate and the injection temperature. The table below provides operational values for these different parameters.

example Range

Preferred advantageous range

Number of cycles (-) 3 2 - 10 1 - 50

Duration of injection (h,

2h 30min to 12h 10min to 24h min)

Si concentration (100 to 200,000 mg)

5Ό00 mg / L 500 to 50Ό00 mg / L

of Si / L of water) mg / L

Water flow (L / min) 0.3 L / min 0.05 to 10 L / min 0.05 to 100 L / min

Injection temperature

55 ° C 50 to 60 ° C 35 - 65 ° C (° C)

Table 1: Values of the various parameters involved in the injection phase

We can define the quantity of silicates injected by the relation:

Ml = Ci · Q · t (1)

Where Ci is the silicate concentration of the input water (g / L)

Q is the flow of water (L / sec)

t is the injection duration (sec)

The "yield of the deposition" is very sensitive to many parameters. It is possible, in fact, to define a yield of silicate deposition by:

Md is the deposited silicate mass (g)

Mi is the injected silicate mass (g) This yield is particularly sensitive to the temperature, but also to the silicate concentration, the duration of the injection, the flow rate, the flow rate and probably other environmental parameters. The yield of the deposition is notably lower in the case of an injection in cold water than in hot water.

The corresponding volume of water to make the deposit can be defined by the relation:

Ve = Md / Ci

Where Ve is the volume of water (m3)

Md is the deposited silicate mass (kg)

Ci is the concentration of silicate injected (kg / m3)

This gives a relationship establishing the effect of the main parameters (yield, concentration, flow and injection time) on the deposited silicate mass.

Note that the deposition efficiency itself also depends on these main parameters (concentration, flow and injection time) as well as environmental parameters, such as pH, hardness, alkalinity, etc., as presented in the equation below. :

μ = μ _(C:, Q t, r...) (4)

The different values proposed in Table 1 are based on the following arguments:

Si concentrations:

Upper limit of 200Ό00 mg of Si / L of water: this is the Si concentration in silicate solutions comprising sodium silicates, in particular Na ₂ SiO ₃ . They are in the form of a viscous liquid. This is the saturation limit; at higher concentrations, saturation crystallization occurs.

Optimum values between 1 Ό00 and 20Ό00 mg of Si / L of water, especially between 2Ό00 and 10Ό00 for injection pump rates typically used in sanitary water installations of buildings. For a maximum flow rate of an injection pump of 6L / h and a water flow rate of 0.3 L / min, this corresponds to a concentration of 5Ό00 mg of Si / L of water.

Injection temperature:

Lower limit of about 35 ° C: the temperature has a strong influence on the crystallization of silicates. Below this temperature, the efficiency of silicate deposition on the inner walls of the pipes becomes too low for an efficient and economical process. Upper limit of 65 ° C: Above 65 ° C, silicates tend to precipitate very rapidly, which can cause injection site deposition, causing two problems: silicates precipitated immediately after injection are no longer available for injection. areas in front and cause a plug at the injection site.

Optimum value around 55 ° C: it is an interesting compromise between inefficiency and too fast precipitation.

The flow of water:

Lower limit of 0.01 L / min: at low flow rates, compensate by increasing the concentration or duration of injection, as can be seen in equation (3).

Upper limit of 100L / min: the boiler must heat cold water, for example 15 ° C, at the injection temperature, for example about 55 ° C. The power consumed by the boiler is proportional to the difference in temperature and the flow of water to be heated as shown in relation (5) below. Thus, the higher the flow rate, the higher the boiler power must be.

Where Q is the heat power delivered by the water heater (W)

m is the mass flow of water (kg / s)

it is the heat capacity of the water = 4185 (J / kgK)

ΔΤ is the temperature difference between the output (K)

and the entrance of the water heater

Another aspect limiting the flow of water is the maintenance of the concentration of silicates. This aspect can be highlighted by inverting the relation (3). An optimum value is around 0.3 L / min, taking into account the constraints described above.

The number of cycles and the duration of the injection:

These two parameters depend mainly on the desired quality of silicate deposition on the wall, given that the available time is limited (generally 24 hours max, or 12 hours max), since it is often preferable not to immobilize a water network during a period of time. long periods, and preferably not more than one day. "

12

The adjustable parameters of the injection process, including the duration of an injection step, the temperature, the concentration of the treatment product, the composition of the treatment product, the duration of the treatment cycle and the flow of water can be essentially identical from one step to another, or may be different from one step to another. For example :

The duration of a step may be longer, and / or at a lower temperature, and / or at a lower concentration than another step, or

• The duration of a step may be longer, and / or at a lower temperature, and / or at a higher concentration than another step, etc.

The variation of the parameters may especially be advantageous between the first injection cycle and the following cycle (s), depending on the condition of the pipes or the cleaning process carried out before the impregnation process. In order to form a uniform, thin first layer serving as a homogeneous hooked surface to assist in the uniform growth of a subsequent layer, there may be an advantage in performing the first cycle at a lower concentration of treatment product than the others. cycles, but possibly longer duration and / or at a different temperature. Indeed, the properties of the inner surface of the pipes before treatment or after cleaning can be very variable along the sanitary water circuit, including materials and geometric irregularities (roughness, roughness) on the surface, the speed of formation of a film on the bare surface of the pipe can be very variable from one part of the pipe to another. Slower growth of the first layer can help to form a more homogeneous film than fast growth. Subsequently, for reasons of efficiency and time saving, the growth of the film can be carried out more quickly since the first layer uniformizes the properties of the surface.

The durations and parameters of the drying cycles can also be substantially identical from one step to another, or they can be different from one step to another. In particular, it may be advantageous for the duration of the last drying cycle to be longer than the previous ones in order to increase the resistance of the impregnating layer before normal return to normal operation, the process being generally more efficient and economical if more drying time is dispensed at the end of the impregnation process.

Referring to Figure 4, the processing of a simple network comprising a hot water or cold water circuit is illustrated. This case may occur for various reasons:

• The building to be treated does not have centralized hot water production but individual boilers. The building therefore only has a cold water circuit. • For various reasons (different degree of corrosion, different materials, ...), it is necessary to treat only hot water or cold water.

In this case, the assembly is ideally carried out as shown in FIG. 4, illustrating a configuration with the following characteristics:

• main pipe 1 at the entrance of the building

• valve 2 to stop the flow in the building

• hot water source 3 (in this example part of the hot water circuit of the sanitary installation) - the water is thus heated by the temperature of the cold water source (for example 10 to 20 ° C ) at the impregnation temperature, for example 55 ° C. The maximum water flow is given by the power of the water heater according to formula (5). Depending on the building equipment, this hot water production can be:

at. The central boiler of the domestic hot water circuit can be operated directly to treat hot water pipes and can be derived to treat cold water pipes. b. If the building does not have a central boiler or its volume or thermal capacity is not sufficient, the element 3 may be a source of external hot water, for example a supplementary water heater.

• tank 4 containing the maintenance product for silicate-based pipes

• maintenance product 5 based on silicate

• suction hose 6 from the maintenance product to the dosing pump

• metering pump 7 for injecting silicates into the main pipe

• silicate feed pipe 8

• anti-return valve 9

• point of injection 10 silicates in the water flow

• 1 1 branches to direct the flow in a bypass

• valve 12 to stop the flow in the main pipe to force its passage through the bypass

• Control tube 13 of the bypass which is removable and which assesses the quality of the deposition of the silicate film after application of the impregnation treatment

• valves 14 to isolate the by-pass of the flow to disassemble for inspection

• derivations 15 feeding the different risers

• valves 16 for isolating or feeding the riser (s) Risers 17 of the sanitary water circuit of a building

• derivations 18 of the different lines

• taps 19 at the end of each pipe.

In the case of several risers 17, it is advantageous to separate or isolate them beforehand with the aid of a valve. This makes it possible to work independently on different circuits of the sanitary water installation of a building and to increase the efficiency of the treatment. Note that in this case, the flow of the main flow can be adjusted by opening the valves. This can be done alternately or in parallel.

Since the water is silicate-laden, its flow in the sinks forms silicate deposits. It is then advantageous to mount a flexible hose at the outlet of the tap making it possible to pour the silicate solution directly into the siphon at the bottom of the sink.

It should also be noted that for cold water pipes, it is advantageous to carry out a cooling before the re-watering in order to preserve the totality of the protective layer.

Referring to Figure 5, the treatment of a dual network including a hot water circuit and a cold water circuit is illustrated. In the case where it is necessary to treat the hot water circuit and the cold water circuit, one can:

• alternately treat the hot and cold water circuit according to the procedure presented in connection with Figure 4;

• or more advantageously to reduce the working time by connecting in series the two circuits to treat them in a single operation as illustrated in Figure 6.

This second approach takes again the principle of treatment presented in figure 4, nevertheless with a modified configuration having the following additional or modified characteristics:

• hot water source 3 comes from the central boiler and not an external booster heater

Flexible hoses 20 make it possible to connect the branches 18 of the hot water circuits to the branches 21 of the cold water circuit

• riser cold water 22

• valves 23 to isolate the various risers cold water

• derivations 24 of the different risers

• risers 25 cold water Diversion 26 making it possible to recover the solution of injected silicates

• 27 silicate recovery pipe

• recovery valve 28 silicates

• isolation valve 29 cold water inlet in the building

The valves 19 are disassembled to connect by means of a hose 20 the bypass of the hot water outlets 18 and the bypasses of the cold water outlets 21. This makes it possible to carry out the impregnation treatment in the hot water circuit 17, 18 and in the cold water circuit 21, 22 of a single injection operation. The silicate solution is then recovered by means of a bypass 26, a valve 28 and a silicate recovery pipe 27.

Referring to FIG. 7, the treatment of a triple network comprising a hot water circuit and a cold water circuit, the hot water circuit having a loop allowing circulation of hot water back to the water heater 3. In the case where it is necessary to treat a triple cold water and hot water network comprising a circulation loop, it is possible to:

proceed according to an approach combining methods presented in relation with figures 4 and 5

proceed according to an approach to treat the triple network in a single operation as presented below.

The diagram of operation is that presented in figure 7. It resumes the principle of that presented in figure 5, nevertheless with a modified configuration having the following additional or modified characteristics:

• hot water circulation line 30 (the circulation pump is not shown in this diagram)

• bypass 31 to recover the silicate solution injected from the circulation pipe

• recovery pipe 33 silicates

• recovery valve 32 silicates

• Isolation valve 34 for the arrival of the circulating water

For this third configuration, in order to carry out the impregnation in one go, the cold water circuit and the circulation circuit can be distributed in parallel, in a procedure similar to that described with reference to FIG.

In the case where it is necessary to treat only a hot water circuit comprising a circulation circuit, the procedure is similar to that shown in Figure 7, however without the cold water circuit. In these diagrams, the direction of flow is always presented hot water to cold water because it is advantageous, the boiler being on hot water, it avoids having to reconnect the pipes to the boiler. It is nevertheless possible to modify the positions of the inputs and outputs of the treatment solution.

Claims

claims

1. A method for treating a sanitary water circulation circuit of a domestic water network, comprising injecting a treatment product comprising silicates in water flowing in said circuit to form a film on the inner surfaces of said circuit to prevent corrosion, oxidation and / or deposition, characterized in that the injection of the treatment product comprises at least one silicate injection cycle, excluding the operation of the water network sanitary, at a concentration between 100 and 200Ό00 milligrams per liter (mg / L) in the water circulating in said circuit for a period between 10 minutes (min) and 24 hours (h), the flow of water flowing in the circuit being adjusted in a range between 0.05 and 100 liters per minute (L / min) and the temperature of circulating water in the circuit being adjusted in a range between 40 and 65 ° C.

2. Method according to the preceding claim, characterized in that the concentration of silicates in the water flowing in said circuit is adjusted between 500 and 50Ό00 mg / l, preferably between 1000 and 20000 mg / l.

3. Method according to one of the preceding claims, characterized in that the duration of an injection cycle is between 30 minutes and 12 hours, preferably between 1 hour and 4 hours, for example around 2 hours.

4. Method according to one of the preceding claims, characterized in that and the flow rate of water flowing in the circuit is adjusted in a range between 0.05 and 10 L / min.

5. Method according to one of the preceding claims, characterized in that the water temperature flowing in the circuit is adjusted in a range between 50 and 60 ° C.

6. Method according to one of the preceding claims, characterized in that it comprises at least two cycles of injection of treatment product, preferably at least three cycles of injection of treatment product.

7. Method according to one of the preceding claims, characterized in that it comprises at least one drying cycle by emptying the circuit water for a period between 5 minutes and two hours, after at least one of the cycles of injection of treatment product.

8. Method according to the preceding claim, characterized in that it comprises a drying cycle after each cycle of injection of treatment product.

9. Method according to one of the two preceding claims, characterized in that the duration of a drying cycle is between 10 minutes and 1 hour, preferably between 20 minutes and 40 minutes, for example around 30 minutes.

10. Method according to one of the preceding claims, characterized in that the sanitary water circulation circuit comprises a cold water circulation circuit, and the method comprises a step of interconnecting the cold water circuit to a cold water circuit. a hot water source configured to circulate hot water in the cold water circuit during injection of the treatment product.

1 1. Method according to the preceding claim, characterized in that the sanitary water circulation circuit comprises the cold water circulation circuit and a hot water circulation circuit, and the method comprises a step of interconnecting the water. cold water circuit to the hot water circuit configured to circulate the hot water in the cold water circuit during injection of the treatment product.

12. The method of claim 10, characterized in that the source of hot water is generated by an external water heater.

13. Method according to one of the preceding claims, characterized in that the silicates are in the form of sodium silicates, including Na ₂ SiO _3.

14. Method according to one of the preceding claims, characterized in that it comprises a cleaning step of the sanitary water circulation circuit before the injection of the treatment product comprising silicates, the cleaning step comprising an injection of acid in the sanitary water circulation circuit.

15. Method according to one of the preceding claims, characterized in that it comprises, after the steps of the preceding claims, a continuous injection of the treatment product comprising silicates in an amount proportional to the volume of water entering the circulation circuit. of sanitary water, the maximum quantity of product injected not exceeding a value fixed by the food standards.